Stroke is the leading cause of adult disability in the United States. One of the most devastating impairments resulting from stroke is aphasia, a language impairment caused by left hemisphere damage involving cortical language areas. Although considerable research effort has focused on increasing aphasia treatment efficacy, most chronic stroke patients with aphasia experience limited recovery. Therefore, enhanced aphasia treatment outcome is of paramount interest as it may improve patients' communication ability and quality of life. Recent studies utilizing animal models suggest that low current transcranial direct current stimulation (tDCS) can locally increase the secretion of brain derived neurotrophic factor (BDNF), a protein that is crucial for induction of brain plasticity. Research i humans has further demonstrated the positive effect of anodal tDCS (A-tDCS) on learning in normal subjects. For the first time, we have shown in a pair of studies how A-tDCS can significantly enhance the effect of the behavioral treatment of anomia (impaired ability to name common objects) in patients with chronic stroke-induced aphasia. Capitalizing on these findings as well as our other research aimed at understanding brain plasticity associated with aphasia treatment, we propose to conduct a Phase II clinical trial to examine the effect of A-tDCS on anomia treatment outcome in patients with chronic stroke. This project will include a randomized, prospective, double-blind trial with two arms (active vs. control) wherein chronically stable stroke patients will receive behavioral aphasia treatment coupled with either A-tDCS or sham tDCS (S-tDCS). Because anomia is the hallmark impairment in aphasia and is present in all aphasic patients, regardless of severity or aphasia type, the primary outcome factor will be anomia severity, defined as the ability to correctly name common objects. The long-term goal of this research is to conduct a Phase III trial to determine if A-tDCS significantly enhances the effect of behavioral aphasia treatment. If the A-tDCS is proven to have a positive effect on aphasia treatment outcome, it is possible that patients who currently receive limited or no treatment benefit may respond to treatment when it is coupled with A-tDCS. Similarly, it is possible that A-tDCS may further boost the treatment effect for patients who respond positively to treatment in the absence of direct brain stimulation. PUBLIC HEALTH RELEVANCE: Stroke is the leading cause of adult disability in the United States; aphasia, an impairment of the ability to process language, is one of the most devastating results of left hemisphere stroke. Most patients with chronic aphasia show very minimal or no benefit following aphasia treatment, emphasizing the need to improve treatment outcome. This research will examine the effect of transcranial direct current stimulation (tDCS), a method that has been shown to improve learning in normal subjects, upon aphasia treatment success.